Telephonic apparatus



Jan. 3, 1956 s. D. M KELLEN 2,729,707

TELEPHONIC APPARATUS Filed June 4, 1951 4 Sheets-Sheet 1 Jan. 3, 1956 s,D, M KELLEN 2,729,707

TELEPHONIC APPARATUS Filed June 4, 1951 4 Sheets-Sheet 2 Mum r08 jamue/0. d'Ael/eh Jan. 3, 1956 5, D, c N 2,729,707

TELEPHONIC APPARATUS Filed June 4, 1951 4 Sheets-Sheet 3 Jan. 3, 1956 sMGKELLEN 2,729,707

TELEPHONIC APPARATUS Filed June 4, 1951 4 Sheets-Sheet 4 /Mjzm UnitedStates PatetitQ TELEPHONIC APPARATUS Samuel Dunseith McKcllcn,Kensington, London, England Application June 4,1951, Serial No. 229,675Claims priority,application Great Britain June 7, 1950 12 Claims.((1179-90) This invention relates to telephonic alarmapparatus forcommunicating a recorded message to a preselected telephoneline uponreceipt of an alarm, as for reporting an outbreak of fire, an attempt atburglary, a rise of flood- Water or the like; such apparatus iscurrently employed in connection with fire and burglary alarms for thepurpose of establishing communication with the fire-service, the policeor the residence of a proprietor or manager, and the apparatus may beassociated with a phonograph or like sound-reproducing means having arecord of a suitable message giving the location of the premises, thenature of the alarm and other particulars recorded in advance. Themessage will be transmitted over the telephone line after the call hasbeen established in the conventional manner by sending trains ofimpulses produced by a rotary dialling drum and cooperating contacts;the dialling drum is conveniently driven by the same motor as therecord. I

The present invention has for its main object to provide improved meansfor operation of the dialling drum in order to call the pre-selectedline to which the message is to be communicated.

Another object of the invention is to provide a movable support for thedialling drum and its co-operating con tacts, the support being normallylocked in a starting position by means of a control device which isreleasable by operation of the motor driving the record, this motorstarting upon completion or interruption of the alarm circuit, accordingto the type of alarm employed, that is, with an open circuit which isclosed by an outbreak of fire or other emergency, or with a closedcircuit which is interrupted by the emergency, the closed circuit typebeing'generally preferred for burglary alarms.

A further object of the invention is to provide an improved device inwhich the dialling drum 'is driven by means of a gear-wheel fast withthe drum, this gear-wheel being brought into engagement with a pinionrevolving with the message record, after the receipt of the alarm hascaused the start of the motor driving the record, the gear-engagementbeing maintained for transmission of the dialling impulses, and thegear-wheel being thereafter displaced from its engagement with thepinion, so that the recorded message can be communicated to the linewhich has been called by the dialling impulses.

A specific object of the invention is to control in proper sequence allthe movements of the support on which the dialling drum, its contactsand the gear-wheel are mounted, by means of a'cam-shaft driven by themotor which starts upon receipt of the alarm.

Other objects and advantages of the invention will hereinafter appearfrom the followingdescription of a preferred embodiment, given withreference to the accompanying drawings, in which: Fig'. l is 'a planview of the device as arranged to employa phonograph record of themessage, showing the "dialling: drum in its terminal position.

Figs. and 3 are partial plan views, showing the dial- ZJZQJQ? Fatente dJan. 3, 1 9 56 2 ling drum brought to its starting and intermediatepositions respectively by the movements of the rocking lever.

Fig. 4 is a rear elevation of the device, showing the cam shaft whichdetermines the movements of the rocking lever.

Fig. 5 is a section on the line 55 of Fig. 1, showing the drive to thecam shaft and the control device locking the rocking lever in itsstarting position.

Fig. 6 is a view of the tone-arm control device operated by thecam-shaft, as seen on the line 6-6 of Fig. 4.

Fig. 7 is a detail of a spring drive for reversing the dialling drum atthe completion of the dialling operation. Figs. 8 and 9 relate to amodification. A

in the illustrated embodiment of the invention, the movements of arocking lever 10 carrying the dialling drum are determined by acam-shaft 11 driven through a Worm-wheel 12 meshing with a worm 13 uponone of the spindles of a phonograph motor. The motor 14 is normally heldstationary by a catch 15 engaging with a peg 16 beneath the turntable17, this catch being disengageable by a relay 18 connected in the alarmcircuit and controlling the exchange line. The cam-shaft is shownprovided with four cams, viz. a cam 19 which releases the control deviceand allows the rocking lever to swing about its pivot, a second cam 20which serves to bring the rocking lever 10 to its starting position(Fig. 2), a third cam 21 which operates a switch to disconnect theinstrument after transmission of the recorded message, and a cam 22which controls the tone-arm 23. i

The lever 10, mounted above the motor casing 24 and adapted to rockhorizontally about a pivot 88 under the action of a spring 89, carriesthe dialling drum 25, which may havea single set of cams for thedialling contacts 26, as in the case where the same digit has to berepeated for establishing the call, for example in dialling 999 in thiscase, the number of repetitions of the digit is controlled by a cursor27 engaging with screw-threads 28 upon a boss 29 integral with the drum25, the axial travel of the cursor as the drum revolves bringing it tothe end of the screw-threads, from which it slips into the path of aprojection 30 revolving with the boss 29. The resultant movement of thecursor displaces a stop-arm 31 upon which it is pivoted at 32 and whichhas served to retain the rocking lever 10 in its intermediate ordialling position (Fig. 3) against the action of the spring 89. Thecursor 27 is urged downwards by a leaf spring 33 pressing down upon itspivot 32; at the same time, it is urged towards the screw-threads 28 bya light spring 34 connecting it to a detent 35 on the opposite side ofthe drum, this detent being pivoted on the rocking lever and normallyengaged at one edge by another projection 36 revolving with the boss 29The two projections may consist as shown of two pins of differentlengths upon the end face of the boss 29. The short pin 30 engages withthe end of the cursor 27 only when the latter occupies a positionsubstantially tangential to the path of the pin after reaching the endof the screw-threads, this position being shown in dotted lines in Fig.3; the longer pin 36 pushes past the detent 35 at every revolution ofthe drum during the dialling operation, but will engage the end of thedetent if the drum turns backwards.

The stop-arm 31 is itself pivoted upon the rocking lever 10 between itspivot or fulcrum 88 and the dialling drum 25, the free extremity 38 ofthe stop-arm being guided to engage with a stop 39 for holding the lever10 in its intermediate position (Fig. 3), a gear-wheel 40 integral withthe drum being then in mesh with a pinion 41 on the turntable spindle42; displacement of the stop-arm 31 by the subsequent thrust of thecursor 27 enables it to slip oil the stop 39 so as to take thegear-wheel out of. mesh with the revolving pinion, this movement of therocking lever to the terminal position (Fig. 1) being limited by theengagement of the same stop 39 by a stepped surface or recess 43 on theextremity of the arm.

In this terminal position of the lever in which its toe 44 has operatedthe jack contacts 45 of the pick-up circuit, the cursor 27 drops back toits original position, ready to engage again with the screw-threads 28,but it is held clear by engagement of its heel 46 by a stop-pin 47 onthe casing.

At the completion of the dialling operation, the drum seeks to return bythe action of an enclosed clockspring 48, until the end of the detentobstructs the second pin 36 and arrests the drum in a position where theplain part of its periphery will engage with the contacts 26. As shownin Pig. 7, the clock-spring 48 is anchored centrally to a peg 49 upon afixed spindle 50 on which the drum 25 is mounted, the outer coils of thespring engaging frictionally with the interior of the drum so as to turnthe latter backwards, up to about one full turn of the drum, after thegear-wheel drive has ceased; the unidi- 5 rectional drive allows thewheel 40 to rotate freely as it is moved past the pinion 41 duringresetting of the lever 10.

This resetting can be performed manually, for example by means of a wiredrawn out by the attendant; preferably however, an initial short run ofthe motor 14, after rewinding by the attendant, is arranged to cause thecamshaft 11 to bring the rocking lever 10 to its starting position, forwhich purpose the turntable is temporarily released. As shown, the cam20 is adapted to engage an oblique face 51 upon a lever 52 pivoted at 53upon the motor casing, the other end of this lever overlying a rocker 54pivoted at 55 upon the casing; the underlying end of the rocker iscranked upwardly at 56, so that when 7 the cam 29 operates the lever 52,the latter will depress this cranked end of the rocker 54 and at thesame time it will tension a spring 57 connected to the stoparm 31 on thelever 10, sufficiently to overcome the spring 89 which is connected tothe toe 44 on the other side of the pivot 88. The movement of the rocker54 raises a peg 58 at its other end from engagement with the toe 44, sothat the lever 10 can swing over to its starting position (Fig. 2) underthe pull of the spring 57.

When the rocking lever 10 has been brought to this starting position,the turntable is stopped by reengagement of the catch 15, leaving theapparatus ready for operation as soon as the alarm circuit energizes therelay 18 to release the catch 15 and connect the apparatus to theexchange line by the jack contacts 59; a short delay,

variable if desired, may be allowed before the further rotation of thecam-shaft 11 causes the cam 19 to release the control lever and startthe dialling operation.

The control lever 60 is adapted to rock over one edge of the motorcasing 24, being pivotally mounted on a bracket 61; its dependent arm 62is engageable by the cam 19 and its upper arm supports a peg 63 whichextends normally up into the path of the lever 10, adjacent to the endwhere the rotary drum is mounted, so as to lock the lever in itsstarting position (Figs. 2 and 5). When the control lever is operated bythe cam 19, it moves the peg 63 clear of the rocking lever to allow thelatter to swing to its intermediate position (Fig. 3); the control leveris held in this released position by the action of a leaf spring 64which has been pressing against the edge of the upper arm and now slipsover it to prevent return of the lever after the cam 19 has passed. Thisleaf spring is so arranged that during the return of the lever 10 at theresetting operation, it drags the leaf-spring 64 clear of the controllever 60 to allow the latter to bring its peg 63 back into position forholding the lever 10 in the reset or starting position, after which theleaf spring returns to press against the edge of the control lever.

The position of the lever 10 maybe displayed by a semaphore devicemounted behind the front panel 65 of the apparatus, as shown in Fig. 1,with a coloured disc visible through a window in the panel and carriedby a lever 66 pivoted at 67; the other arm of the lever has an inclinedupper edge 68 engaged by a wire 69 projecting from the lever 10, so thatthe resetting of the latter lifts the semaphore disc into place behindthe window. Upon the same panel 65, there is mounted a push-button 7%for operating jack contacts 71 to energize the relay l3; when theapparatus is to be reset after an operation of the alarm, the motor 14will be rewound by means of a handle and the button will then be pushedto start the turntable, the motor being allowed to run until the cam 20has brought the rocking lever 10 to its starting position (Fig. 2). Assoon as this is heard to have occurred, the button 70 will be released,leaving the apparatus ready for operation, with the semaphore discvisible to show its condition.

The tone-arm 23 supporting the pick-up is returned to its startingposition with the needle in contact with the record, before transmissionof the recorded message, the cam 22 having one face which serves toraise the tonearrn spindle '72; at the end of this upward movement, thespindle is caused to swing the tone-arm back to the starting point ofthe record, the tone-arm then falling to bring the needle into contactwith the record as soon as the opposite face of the cam allows thespindle to descend again. Preferably the tone-arm 23 is lifted and swungat least partly back to its starting position by the preliminarymovement of the camshaft 11 at the setting of the apparatus.

As seen in Figs. 4 and 6, the cam 22 engages with the rounded foot 73 ofa slider 74 having two bosses 75 in which the spindle 72 is rotatablymounted; a sleeve 76 secured to the upper end of the spindle carries thetonearm 23 The slider 74 is supported in guides 77 upon a standard 78having a U-shaped bracket 79 secured thereto; the middle portion of thisbracket is slotted out to receive a peg 8t) fixed in a collar 81 securedupon the spindle 72. The width of the slot 82 limits the swing of thetone-arm, its lower edge being horizontal and its upper edge 83inclined; when the spindle is lifted by the cam 22, the peg contactswith this inclined edge 83 and forces the spindle to turn so as to swingthe tone-arm to the starting point of the record. The descent of thespindle, when the cam 22 passes from under the slider 74, takes placevertically under control of a pivoted latch 84 of substantially sectorshape, normally held with one edge parallel to the sides of the slot 82by a light spring 85; as the peg 80 travels up the inclined edge 83 ofthe slot, it lifts this latch until clear of the bottom corner thereof,whereupon the latch snaps down behind the peg, so that the peg andspindle can only descend vertically.

In operation, assuming that the apparatus has been reset with thetone-arm raised and swung over to the starting point of the record, thelever 10 being in its starting position, the alarm circuit will causethe relay 18 to connect the instrument to the exchange line by way ofthe contacts 59, and to disengage the catch 15 beneath the turntable;the motor 14 can then drive its mechanism for revolving the turntableand the cam-shaft 11 will begin to rotate. After a short delay, forexample ten seconds, as determined by the angular setting of the cam 19,the control lever 69 will lower its peg 63 and allow the lever 10 torock under the action of the spring 57 until it reaches its intermediateposition (Fig. 3); the lever is arrested in this position by theabutment of the stop-arm 31 against the pin 39. As the gear-wheel 4i)revolves, the cams upon the periphery of the drum 25 successively engagewith the dialling contacts 26 and transmit the coded impulses threetimes; during the three revolutions of the drum, the cursor 27 advancesalong the screw-threads 23 until it reaches the top, whereupon it rocksover to bring its extremity into the path of thepin 30. Consequently, atthe completion of this third revolution of the drum, the pin 30 causesthe cursor to move the stop-arm 31 sidewaysgia rela'tion-tothe pin 39,the leverlo being thus tree to rock'to its terminal position (Fig. 1);the gear wheel 40 is then clear of the revolving pinion, the stopa'rm 31engages the pin 39 within the stepped recess 43, and the detent 35engages the pin 36 so as to hold the dialling drum in correct positionfor its next operation. As soon as the rocking lever reaches itsterminal position, its toe 44 engages the jack contacts 45 for'thepick-up circuit; by this time, the cam 22 will have lowered the tone-arm23 to bring the needle down upon the re v'olving record and thetransmission of the message will begin. The message may be repeated twoor more times upon the'rec'ord to allow for delay in establishing "oranswering the telephone call.

In order to disconnect the telephone line and pick-up circuit after thetransmission of the recorded message, the carn'21 nowoperates to closecontacts 36 which cause the relay 18 to free the catch 15, therebyarresting the turntable, and to restorethe jack contacts 59 to theiroriginal p'osition. Alternatively, the customary slowing down of themotor 14 at theend of the record may be utilized by providing a leverwhich engages with the speed disc 87 of the governor; this lever'willhave a short forked arm which rocks as the motor speeds up, therebydragg'ing a spring pawl at the end of its longer arm across the hump ofa spring contact controlling the circuits, for example through asuitable relay, but when the motor slows down towards the end of therecord, the forked lever will return the pawl across the humped contact,the pawl acting positively in this direction of movement to depress thespring contact and establish the relay circuit.

The rotary dialling drum having peripheral cams for repeating the samelarge number of impulses at every revolution may be fitted in the knownmanner with'a sleeve or shield which cuts 01f some of the cams fromengagement with the co-operating contacts, so as to reduce the number ofimpulses in each train. Where the telephone call to-be establishedrequires the use of diiferent digits instead of repeating the same digiteach time, the rotary drum may be arranged to provide for the severaldigits on two or more'sets of cams, the drum being for example displacedaxially in relation to the contacts between its rotary movements by anyconvenient means. i

Figs. 8 land 9 illustrate a modified dialling drum 90, in which thescrew-threads 91 engaged by the cursor 27 are formed with peripheralcams 92 upon the crests of the threads for engaging the diallingcontacts 26; the latter are mounted upon a finger 93 which is carried bythe same pivot 32 as the cursor and travels longitudinally of the drumat the same time as the latter. The number of cams on the severalthreads may be the same or difierbut, as requ'ired'by'the digits to betransmitted, and the number of screw-threads may also be as required,accordin'g to the number of le'tters-and/ or digits in the call-sign.The pivot 32 is pressed downwards by a leaf spring 33 and the cursor 27is urged towards the threads by a light spring 34; the finger 93 is alsourged towards the threads by a light spring 94, its movement into thegrooves being limited by a fixed post 95 so that the springs 26 engageproperly with the cams.

As shown in Fig. 8, the cursor 27 and finger 93 are coupled togetherwith lost motion by a peg 96 projecting from the cursor into a notchupon the boss 97 of-the finger, so that the cursor can swing over thetop of the ,drum after reaching the end of the screw threads, while thefinger 93 still remains engaged therein at a lower level; on'thesubsequent return of the cursor, when it is pushed back by the revolvingprojection 30, so as to displace the stop-arrn 31,11; previouslydescribed, the cursor acts to swing the finger 93 away from the diallingdrum so as to lift the contacts 26 clear of the cams thereon, the cursorand finger then descending to their original levels under the pressureof the spring 33.

It will be understod that the rotary dialling drum maybeureadilyfi-removed and replaced. :by another having a differentarrangement of cams, whenever it is desired to provide for communicationwith a different subscriber-7s line.

What I claim is:

1. In telephonic alarm apparatus of the class described, including acall transmitter and a motor-driven record of a message to becommunicated to a pre-selected line after calling, a call transmittercomprising a dialling drum, contacts co-operating with said drum, agear-wheel fast with said drum, a movable support for said drum,contacts and gear-wheel, a pinion rotatable'by rotation of saidmotor-driven record, means .for retaining said support in a startingposition wherein said gear-wheel is clear of said pinion, means formoving'said support .toa dialling position wherein said gear-wheelengages with said pinion, means .for retaining said support in saiddialling position during transmission of the dialling impulses, andmeans for displacing'said support from said dialling position aftertransmission of said impulses.

2. In telephonic alarm apparatus of the class described, including acall transmitter and a motor-driven record of a message to becommunicated to a pro-selected line after calling, a call transmittercomprising a dialling drum, contacts co-operating with said drum, agear-wheelfast with said drum, a movable support for said drum, contactsand gear-wheel, a pinion'rotatable by rotation of said motor-drivenrecord, means for retaining said support in a starting position whereinsaid gear-wheel is clear of said pinion, means for moving said supportto a dialling position wherein said gear-wheel engages with said pinion,means for retaining said support in'said .dialling position duringtransmission of the dialling impulses, means for displacing said supportfrom said dialling position after transmission of said impulses, and'acam-shaft controlling said support-retaining, moving and displac: ingmeans, said cam-shaft being driven by said motor simultaneously withsaid pinion.

3. In telephonic alarm apparatus of the class described, including acall transmitter and a motor-driven record of a message to becommunicated to a pre-selected line after calling, a call transmittercomprising a dialling drum, contacts co-operating with said drum, arockable support for said drum, contacts and gear-wheel, a pinionrotatable by rotation of said motor-driven record, means for retainingsaidsupport in a starting position wherein said gear-wheel is clear ofsaid pinion, means for moving said support to a dialling positionwherein saidgear-wheell'is centered upon astraight line joining thepivotal axis of said rockable support to the axis ofsaid pinion, saidgear- .wheel meshing with said pinion insaid dialling position, meansfor retaining said support in said dialling position duringtransmission. of the diallingimpulses, and means for displacing saidsupport from said dialling position after transmission ofsaidimpulses.

t. In telephonic alarm. apparatusof the class described, including acall transmitter and 'aim'otor-driven record of a message .to becommunicated to a pre-s'elected line after calling, a' call transmittercomprising a dialling drum, contacts co-operating with said drum,agear-wheel fast'with said drum, a movable support for said drum,contacts and gear-wheel, a pinion rotatable by rotation of saidmotor-driven record, means for .retaining'said support in a startingposition wherein said-gea'r-wheel is clear of said pinion,meansforzmoving said support to a dialling position'wherein saidgear-wheel engages with said' pinion, means for retaining said supportin said dialling position during transmission of the dialling impulses,screw-threadsfast with said drum, -a spring-controlled cursor" engagingwith, said 'screwth'r'eads and travelling therealong during rotation ofsaid'drum', 'and mea'ns for displacing said support from said diallingposition when said cursor reaches the end of said screw-threads.

5. In telephonic alarm apparatus of the class described, including acall transmitter and a motor-driven record of a message to becommunicated to a pre-selected line after calling, a call.transmittercomprising a dialling drum, contacts co-operating with said drum, agear-wheel fast with said drum, a movable support for said drum,contacts and gear-wheel, a pinion rotatable by rotation of saidmotor-driven record, means for retaining said support in a startingposition wherein said gear-Wheel is clear of said pinion, means formoving said support to a dialling position wherein said gear-wheelengages with said pinion, a stop-member attached to said support, afixed abutment for said stop-member, said stop-member engaging saidabutment to retain said support in said dialling position duringtransmission of the dialling impulses, screw-threads fast with saiddrum, a spring-controlled cursor engaging with said screw-threads andtravelling'therealong during rotation of said drum, and means rotatingwith said'drum for engaging said cursor when it reaches the end of saidscrew'threads and causing it to shift said stop-member in relation tosaid abutment, said moving means then displacing said support from saiddialling position.

' 6. In telephonic alarm apparatus of the class described, including acall transmitter and a motor-driven record of a message to becommunicated to a pre-selected line after calling, a call transmittercomprising a dialling drum, contacts co-operating with said drum, agear-wheel fast with said drum, a movable support for said drum, contacts and gear-wheel, a pinion rotatable by rotation of. saidmotor-driven record, means for moving said support to a startingposition wherein said gear-Wheel is clear of said pinion, means forretaining said support in said starting position, means for moving saidsupport to a dialling position wherein said gear-wheel engages with saidpinion, means for retaining said support in said dialling positionduringtransmission of the dialling impulses, i

means for displacing said support from said dialling position aftertransmission of said impulses, and a cam-shaft controlling saidsupport-moving, retaining and displacing means, said cam-shaft beingdriven by said motor simultaneously with said pinion.

7. 1n telephonic alarm apparatus of the class described, including acall transmitter and a motor-driven record of a message to becommunicated to a pre-selected line after calling, a call transmittercomprising a dialling drum, contacts co-operating with said drum, agear-wheel fast with said drum, a movable support for said drum,contacts and gear-wheel, a pinion rotatable by rotation ofsaidmotor-driven record, means for operation of said drum comprising agear-wheel fast with said drum, a

movable support for said drum, contacts and gear-wheel, a"

a pinion rotatable by said motor, means for retaining said support in' astarting position wherein said gear-wheel is clear of said pinion, meansfor moving said support to a dialling position wherein said gear-wheelengages with said pinion, means for retaining said support in saiddialling position during transmission of the dialling impulses,screW-threads fast with said drum, a spring-controlled cursor engagingwith said screw-threads and travelling therealong during rotation ofsaid drum, said cursor controlling the co-operation of said diallingdrum with said contacts, and means for displacing said support from saiddialling position when said cursor reaches the end of saidscrew-threads.

8. ln telephonic alarm apparatus of the class described, a dialling drumhaving peripheral cams representing a digit to be dialled repeatedly bycontinuous rotation of said drum, screw-threads fast with said drum, aspringcontrolled cursor engaging with said screw-threads and travellingtherealong during rotation of said drum, and means for interrupting therotation of said drum when said cursor reaches the end of saidscrew-threads.

lit)

9. In telephonic alarm apparatus of the class described, a dialling drumhaving peripheral cams representing a digit to be dialled repeatedly bycontinuous rotation of said drum, a gear-wheel fast with said drum, amovable support for said drum and gear-wheel, a pinion for driving saidgear-wheel, a stop-member for retaining said support in a positionwherein said gear-wheel engages with said pinion, screw-threads fastwith said drum, a springcontrolled cursor engaging with saidscrew-threads and travelling therealong during rotation of said drum,said cursor being mounted on said stop-member, and means carried by saiddrum for engaging said cursor when it reaches the end of saidscrew-threads, said engaging means then causing said cursor to shiftsaid stop-member from its retaining position.

10. In telephonic alarm apparatus of the class described, a diallingdrum having peripheral cams representing a call sign to be dialled byrotation of said drum, screw-threads fast with said drum, aspring-controlled cursor engaging with said screw-threads for relativeaxial travel during rotation of said drum, and means for interruptingthe rotation of said drum when said cursor reaches the end of saidscrew-threads.

11. In telephonic alarm apparatus of the class described, a diallingdrum having peripheral cams representing a call sign to be dialled byrotation of said drum, screw-threads fast with said drum, aspring-controlled cursor engaging with said screw-threads for relativeaxial travel during rotation of said drum, a clock-spring in frictionalengagement with said drum, said clock-spring being wound up by rotatingof said drum, and means for interrupting the rotation of said drum whensaid cursor reaches the end of said screw-threads, said clock-springthen acting to rotate said drum in reverse direction to obtain aninoperative position of said peripheral cams.

12. in telephonic alarm apparatus of the class described, including acall transmitter and a motor-driven record of a message to becommunicated to a pre-selected line after calling, a call transmittercomprising a dialling drum, contacts co-operating with said drum, agear-wheel fast with said drum, a movable support for said drum,contacts and gear-wheel, a pinion rotatable by rotation of saidmotor-driven record, a clock-spring having frictional engagement withsaid drum, said clock-spring being wound up by rotation of said drum bysaid pinion and tending to rotate said drum in reverse direction, meansfor retaining said support in a starting position wherein saidgear-wheel is clear of said pinion, means for moving said support to adialling position wherein said gear-wheel engages with said pinion,means for retaining said support in said dialling position duringtransmission of the dialling impulses, and means for displacing saidsupport from said dialling position after transmission of said impulses,said gear-wheel rotating said drum in reverse direction to overrun saidclock-spring when said gearwheel engages with said pinion during returnof said support to said starting position.

References Cited in the tile of this patent UNITED STATES PATENTS1,867,500 Denzler July 12, 1932 1,974,551 Tuscher et al. Sept. 25, 19342,036,420 Lowry et al. Apr. 7,1936 2,099,913 Tuscher et al. Nov. 23,1937 2,131,565 Lauersdorf Sept. 27,1938 2,161,525 Mountstephen June6,1939 2,276,954 Pritts et al. Mar. 17, 1942 2,358,586 Newell Sept. 19,1944 2,469,278 Sears May 3,1949 2,537,599 Mountstephen J an. 9, 1951

